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Efficacy of fibrin-assisted soft-tissue promotion (FASTP) in treatment of multiple gingival recession defects: a retrospective 3-D volumetric analysis

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Efficacy of fibrin-assisted soft-tissue promotion (FASTP) in treatment of multiple gingival recession defects: a retrospective 3-D volumetric analysis

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Content EFFICACY OF FIBRIN-ASSISTED SOFT-TISSUE PROMOTION (FASTP)
IN TREATM ENT OF MULTIPLE GINGIVAL RECESSION DEFECTS:
A RETROSPECTIVE 3-D VOLUMETRIC ANALYSIS
By
Navid Nobaharestan, DDS
A Thesis Presented to the
FACULTY OF THE USC HERMAN OSTROW SCHOOL OF DENTISTRY
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
MASTER OF SCIENCE
CRANIOFACIAL BIOLOGY
August 2020
ii
TABLE OF CONTENTS

List of Tables…………………………………………………………………………………… iii

List of Figures……………………………………………………………………………………iv
Abstract…………………………………………………………………………………………. vi
Background……………………………………………………………………………………....1
Objectives…………………………………………………………………………………….… 9
Materials & Methods …………………………………………………………………………...10
Results…………………………………………………………………………………………. 15
Discussion…………………………………………………………………………………...… 16
Conclusions…………………………………………………………………………………..... 24
References……………………………………………………………………………………... 25
Tables………………………………………………………………………………….…….… 32
Figures…………………………………………………………………………………….…... 37

iii
List of Tables:

Table 1: Demographic of the sample population …………………………………………….32
Table 2: Descriptive statistics of defect characteristics ………………………………………33
Table 3: Volumetric changes distribution for each tooth position group …………………….34
Table 4: Predicted marginal mean differences in volume change (mm
3
) ……………………35
Table 5: Correlation between baseline measurements and volume change ………………….36

iv
List of Figures:

Figure 1.1. Comparative release of PDGF from PRP, L-PRF, and A-PRF over 10 days after
preparation (Kobayashi et al. 2016)…………………………………………………………37
Figure 1.2. Comparative release of TGF-β1 and VEGF from PRP, L-PRF, and A-PRF over 10
days after preparation (Kobayashi et al. 2016)………………………………………………38
Figure 1.3. Comparative release of EGF and IGF from PRP, L-PRF, and A-PRF over 10 days
after preparation (Kobayashi et al. 2016)……………………………………………………39
Figure 2: Advanced Platelet Rich Fibrin (A-PRF) membrane preparation. A: fibrin clot
dissociation from red blood cells after centrifugation, B: fibrin clots, C: fibrin membranes after
compression…………………………………………………………………………………40
Figure 3: Treatment of multiple adjacent gingival recession defects (RT1 & RT2) with FASTP
protocol. A: Baseline, B: vestibular incision, C: Tension-free coronal advancement through
vestibular incision, D: root surface preparation with 17% EDTA, E: introduction of A-PRF
membranes through the vestibular incision, F: clinical presentation after placing 3-4 A-PRF
membranes per pair of treated teeth, G: Apical periosteal mattress sutures, H: interproximal
resin assisted sutures, I: 24-month postoperative presentation……………………………..41
Figure 4: 3-Dimentional Image Translated from Intraoral Scan. A: Cropped image of the pre-
operative condition B: Cropped image of the post-operative condition C: Image A and B
superimposed D: Cross-section (sagittal plane) mid facial tooth #8 to confirm superimposition E:
Cropped facial view of pre-operative tooth #8 F: Red = recession surface area, Arrows = defect
v
depth and width G: Cropped facial view of post-operative tooth #8 H: 3-D view of cropped pre-
operative tooth #8 I: 3-D view of cropped post-operative tooth #8…………………………42
Figure 5: Mean volumetric changes (mm
3
) distribution for each tooth position group…….43
Figure 6: Mean volumetric changes (mm
3
) for each tooth position group…………………44

vi
ABSTRACT

Background: A variety of surgical techniques and biomaterials have been introduced to treat
multiple adjacent gingival recession defects. While there is an abundance of clinical studies
reporting 2-dimensional changes after root coverage procedures, data on evaluating 3-
dimensional changes is scarce. The primary aim of this retrospective study is to assess the
volumetric changes around teeth with gingival recession defects with Fibrin-Assisted Soft Tissue
Promotion (FASTP) technique using Advanced Platelet Rich Fibrin (A-PRF) membranes. The
secondary aim was to analyze the correlation between baseline defect depth, width, surface area,
tooth position and the volumetric changes after healing.
Methods: This study is designed as a retrospective analysis. Pre- and post-operative intraoral
scans of 10 patients (144 teeth: 23 RT1 + 121 RT2) treated with FASTP were digitally
superimposed to quantify volumetric changes around each treated tooth.
Results: The mean volume gain per tooth in a descending order was 16.4 ± 32.6 mm
3
at
maxillary canines, 14.8 ± 32.6 mm
3
at maxillary incisors, 7.8 ± 9.1 mm
3
at mandibular
premolars/molars, 6.2 ± 16.4 mm
3
at maxillary premolars/molars, 3.9 ± 11.0 mm
3
at mandibular
canines, and 1.8 ± 7.7 mm
3
at mandibular incisors. Maxillary canine had significantly more
volume gain than mandibular teeth (p<0.05). In the maxilla, canines had significantly more gain
than the posterior teeth (p<0.05). Maxillary incisors had significantly more gain than mandibular
incisors (p = 0.01). No statistically significant correlation was found between baseline recession
depth, width, surface area, and volume gain.
Conclusion: The present findings suggest that FASTP technique may be used for root coverage
therapy at sites that present with keratinized gingiva.
1
BACKGROUND

Gingival recession is a clinical condition associated with displacement of the gingival
margin apical to the cemento-enamel junction (CEJ) (1). This condition is a clinical attachment
loss and could present on one site (localized) or multiple sites (generalized).
The prevalence of gingival recession has been shown to affect more than 50% of the US
population, and more than 85% of the population 65 years of age or greater (2). Gorman (1967)
reported that 78% to 100% of middle-aged individuals in the USA present with gingival
recession defects, affecting 22% to 53% of the teeth (3).
Different classification systems have been introduced to classify gingival recession
defects. Most studies use the system introduced by Miller, in which he proposed four classes of
gingival recession based on the level of the gingival margin, mucogingival junction, and
interproximal alveolar bone (4). In Miller class I defects, marginal tissue recession does not
extend to the mucogingival junction, and there is no periodontal loss in the interproximal area. In
class II defects, marginal tissue recession extends to/beyond the mucogingival junction and there
is no periodontal loss in the interproximal area. In class III defects, marginal tissue recession
extends to/beyond the mucogingival junction and there is bone/soft tissue loss in the
interproximal area. In class IV defects, marginal tissue recession extends to/beyond the
mucogingival junction with severe bone/soft tissue loss in the interproximal area. Furthermore, it
was suggested that complete root coverage was feasible for class I and II defects, partial root
coverage for class III defects, and no root coverage was possible for class IV defects.
The Miller classification system has been widely used in both clinical and research
settings, but it also has some limitations. These limitations include the difficulty to differentiate
between class I and II defects, the use of bone or soft tissue loss as an interdental reference for
2
periodontal destruction, and the potential of root coverage with the new advancements in
therapeutic approaches (5).
In 2011, Cairo introduced a new classification system in which he proposed three classes
of gingival recession types based on the interproximal clinical attachment level (6). In recession
type 1 (RT1), gingival recession presents with no loss of interproximal attachment, and the
interproximal CEJ is not clinically detectable. Recession type 2 (RT2) is associated with a loss of
interproximal attachment, in which the amount of interproximal attachment loss is less than or
equal to the buccal attachment loss. Recession type 3 (RT3) is also associated with loss of
interproximal attachment, however, the amount of interproximal attachment loss is greater than
the buccal attachment loss. One-hundred percent coverage can be predicted in RT1 defects.
Several randomized clinical trials have shown 100% root coverage can be possible when
applying certain root coverage procedures in RT2 defects. However, in RT3 defects, complete
root coverage is not achievable (7).
Gingival recession is a multifactorial condition. Gingival inflammation and traumatic
tooth brushing are known as the main etiological factors of this condition (8, 9, 10, 11). The
progression of recession defects may be influenced by several factors including tooth
malposition, thin tissue biotype, high frenum attachment, presence of non-carious cervical
lesions, prior history of periodontal surgery, orthodontic movement, defective restoration, and
history of smoking (12, 13).
Throughout the last 6-7 decades, a variety of techniques and materials have been
introduced for the treatment of gingival recession as a means to gain root coverage, enhance
periodontal maintenance, improve esthetics, increase soft tissue thickness, prevent root caries,
3
prevent non-carious cervical lesions caused abrasion and erosion, decrease root sensitivity, and
halt the progression of gingival recession defects (14, 15). In 2016, Chambrone and Tatakis
reported in their systematic review that when gingival recession defects were left untreated, they
would not improve spontaneously. Seventy-eight percent of the untreated sites progressed in
recession depth, and 79% of the patients with untreated gingival recessions developed new
recession sites (15).
Lang and Loe pioneered the concept that there is a relationship between the width of
keratinized gingiva and the state of inflammation in the periodontium (16). They reported the
presence of a minimum of 2mm of attached gingiva is critical for maintenance of periodontal
health. Therefore, the lateral sliding graft (17), epithelialized palatal graft (free gingival graft -
FGG) (18), and double papilla repositioned graft (19) procedures were introduced to augment
keratinized tissue around teeth. Later, it was well documented that oral hygiene and plaque
control play a bigger role in maintenance of periodontal health regardless of the width of
keratinized tissue (20, 21, 22).
Eventually, the objective of gingival graft procedure shifted from augmentation of
keratinized tissue to root coverage. An array of techniques with their modifications have been
proposed with this aim. These include the following: Coronal advancement flap (CAF) following
FGG procedure (23), Coronal advancement flap over subepithelial connective tissue graft (24),
double pedicle graft over subepithelial connective tissue graft (25), envelope flap (26),
intrasulcular tunneling (IST) (27), modified coronal advancement flap (28), Vestibular incision
subperiosteal tunnel access (VISTA) (29), and Modified microsurgical tunnel technique (30).
4
On the other hand, a wide range of biomaterials have been proposed to be used in
conjunction with these root coverage procedures. These include: autogenous subepithelial
connective tissue graft (31, 32, 33), Allograft (i.e. acellular dermal matrix grafts (ADMG)) (34,
35), xenograft (i.e. collagen membranes) (36, 37), enamel matrix derivative (EMD) (38), and
collagen bilayer matrix (39).
Based on the 2015 AAP Regeneration Workshop, the most reported approaches for the
treatment of gingival recession since the 1990s have been subepithelial connective tissue (SCTG)
based procedures, CAF, ADMG + CAF, and EMD + CAF (21, 40). The findings of 75 RCT (115
treatment groups) published between 1993 and 2017 showed an overall mean root coverage of
83.34% ± 12.46%, with a range of 41.80% to 99.30% (41). It was demonstrated that all root
coverage procedures could result in a significant reduction in recession depth and CAL gain in
Miller I and II defects. Moreover, comparing different therapeutic modalities since 1990, there
has been an increase in the mean root coverage over time. It was also reported that CTG based
procedures provide the best clinical outcomes. Besides the addition of a CTG, atraumatic flap
dissection and tension free flap stabilization appear to be elements for the achievement of early
and positive results.
The destruction of periodontium associated with gingival recession can be localized on
one tooth or multiple adjacent teeth. Despite the observation that gingival recessions are most
often a generalized condition, most reviews and meta-analyses have been reporting the clinical
outcome of localized defects (42). This suggests that more clinical trials are needed to assess the
efficacy of different therapeutic modalities on multiple adjacent affected teeth.
5
There have been several studies evaluating different factors that affect the clinical
outcome of root coverage procedures. These factors can be classified as patient’s factors
(medical history, smoking status, periodontal health), anatomical factors (interproximal bone
level, dimensions of papilla, recession defect size, soft tissue phenotype, location of the tooth),
and surgical factors (surgeon’s experience, surgical technique, choice of biomaterials) (44, 45,
46).
It is generally reported that a thin soft tissue phenotype is more prone to develop gingival
recessions than do thick ones (47). Therefore, improving the soft tissue phenotype by increasing
the thickness of tissue has become one of the objectives of root coverage procedures. Gingival
thickness ranges from 0.63 mm to 1.79 mm. An overall thinner gingiva has been observed
around canines with the mean of 0.80 mm (48). In a systematic review by Hwang and Wang HL,
flap thickness was reported as a predictor of root coverage (49). Also, in the classic literature,
Baldi demonstrated that flap thickness of more than 0.8 mm can be a strong predictor of
complete root coverage (50).
From a clinical point of view, connective tissue grafts may be utilized to treat any kind of
recession, but selective approaches should be considered to prevent ‘overtreatment’ (i.e.,
thickening of gingiva at sites already presenting gingival thickness of greater than 0.8 to 1.00
mm) (41). For years, connective tissue grafts have been known as the gold standard in treatment
of gingival recession defects. However, considering concerns with patient morbidity, and
limitation in amount of donor tissue, are factors to find substitute graft materials for autogenous
connective tissue graft (21).
6
Several studies have focused on the use of biological agents or growth factors as a means
to promote cell recruitment, differentiation, and matrix biosynthesis to regenerate lost
periodontium (51). Enamel matrix derivative, Platelet-derived growth factors, fibroblast growth
factor-2, and platelet concentrates are examples of the most studied biological agents in this
field.
Platelet concentrates have been introduced to regenerative medicine for over two
decades. In medicine, they’ve been used in treatment of acute and chronic injuries of the bone
and cartilage, plastic surgery, orthopedic and sports medicine. In dentistry, platelet concentrates
have been used in a variety of surgical therapies (52). Examples include regeneration of
periodontal defects, treatment of hyperplastic gingival tissues, alveolar bone augmentation,
extraction sockets, palatal wound closure, and treatment of gingival recession defects. In early
studies, the original protocol utilized a two-step centrifugation procedure with the addition of
anticoagulants to prevent blood coagulation prior to centrifugation (53). This product is known
as platelet-rich plasma (PRP). Despite the widespread use of PRP in fields of medicine and
dentistry, the complicated preparation protocol, addition of anticoagulation factors and its impact
on blood coagulation and healing, and short-term release of growth factors all lead to the
development of the new generation of platelet concentrates (54, 55).
In 2001 Choukroun et al. introduced the development of new platelet concentrates
without incorporation of anticoagulation factors (56). This new formulation was later known as
platelet-rich fibrin (PRF). In the absence of anti-coagulants, PRF forms a 3- dimensional scaffold
following 10–12min of centrifugation at 200–700g force. PRF matrix is a concentrate of
platelets, leukocytes, growth factors and cytokines including transforming growth factor-beta1
7
(TGF-β1), platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF),
insulin-like growth factors (IGF), interleukin(IL)-1β, IL-4, and IL-6 (57). These factors act
directly on inducing the proliferation and differentiation of osteoblasts, endothelial cells,
chondrocytes, and fibroblasts (58, 59). Alpha granules that are secreted by platelets get trapped
in the fibrin matrix. These trapped granules have been shown to secrete their growth factors in a
sustained-release fashion over 15 days (60). In regenerative therapies, PRF can act as both a
scaffold and a reservoir of autogenous living cells and growth factors (61).
Based on the processing speed and duration, PRF is classified as Advanced-PRF (A-
PRF), Leukocyte-PRF (L-PRF), Injectable-PRF (I-PRF), and Titanium prepared PRF (T-PRF).
Kobayashi et al. showed that the lower centrifugation speed and duration protocol used in
preparation of A-PRF yield in a significant increase in growth factor release (62). In another
study by Kobayashi et al., they investigated the release of growth factors from PRP, L-PRF, and
A-PRF (63). This study exhibited that PRP released the highest amount of growth factors over
the first 15 minutes after preparation. However, A-PRF growth factor release increased
throughout the first 8 hours after preparation and surpassed PRP and L-PRF groups. Moreover,
they showed that A-PRF had a more gradual and sustained growth factor release up to 10 days
after preparation. It was also shown that A-PRF had the highest total growth factor release when
compared with PRP and L-PRF (Figure 1.1-1.3). Ghanaati et al. also investigated the different
properties of L-PRF and A-PRF. Their study showed that A-PRF clots had a looser structure,
more interfibrous space, and more living cells when compared with L-PRF (64). In addition,
these cells were more evenly distributed throughout the A-PRF clots. These findings suggest that
utilizing A-PRF may provide superior clinical outcome in regenerative periodontal therapies.
8
Based on these results, in 2017, Aalam et al. published a new technique known as,
“Fibrin-Assisted Soft-Tissue Promotion (FASTP)”, for treatment of multiple adjacent gingival
recession defects (65). This technique was proposed as a modification of Vestibular Incision
Subperiosteal Technique Access (VISTA) with the use of A-PRF.

9
OBJECTIVE
The aim of this two-part retrospective study is to evaluate the efficacy of the Fibrin-
Assisted Soft-Tissue Promotion technique as a treatment modality of multiple gingival recession
defects in a clinical setting. This part of the study focused on the 3-dimensional changes in soft
tissue after 6-18 months after therapy.
Our primary null hypothesis was: There is no volume gain in the soft tissue after treating
gingival recession defect with Fibrin-Assisted Soft-Tissue Promotion technique.
Our secondary null hypothesis was: There is no correlation between recession defect depth,
width, surface area, tooth position and volumetric change after healing.

To test these hypotheses, we developed 2 specific aims:
1. Quantifying the 3-dimentional volumetric changes around each tooth after therapy.
2. Analyzing the correlation between baseline parameters including defect depth, width,
surface area, tooth position and the volumetric changes after healing.

10
MATERIALS & METHODS
Study Design:
The protocol of this retrospective study was reviewed and exempted by the Institutional
Review Board of the University of Southern California. The study was conducted by a resident
in the advanced periodontology department based on the intraoral scans of patients who
underwent the treatment of multiple gingival recession defects using FASTP technique in the
private periodontal practice of one of the co-investigators of the study (A.A.A.). These patients
were treated by a single experienced periodontist between 2017-2019 as a part of their routine
care. All the measurements were performed using a reverse engineering software (Geomagic
Control X). The main outcome variable was volumetric changes of gingival tissue after healing.
Initial recession width, depth, tooth position (maxillary posterior, mandibular posterior,
maxillary canines, mandibular canines, maxillary incisors, mandibular incisors) and their
relationship with the primary outcome were also evaluated.
Study Population:
The dental records identified 13 patients meeting the inclusion and exclusion criteria. Out
of these 13 patients, the records of 10 patients (144 teeth) could be used for 3-dimensional
analysis. The mean follow-up period was 12.2 ± 4.6 months (range 6-18 months). Tables 1
summarizes the demographic of the 10 studied patients.
Inclusion Criteria:
Availability of intraoral scans at baseline and follow up (6-18months)
Patients with ambulatory medical history (ASA 1 and ASA 2)
Patient diagnosed with RT 1, 2, 3 buccal gingival recession on multiple adjacent teeth
Gingival recession defects treated with FASTP surgical protocol and A-PRF
11
Exclusion Criteria:
Patients with uncontrolled periodontitis
Non-diagnostic intraoral scans
First and second molars
Smoking was not an exclusion criterion. Nonetheless, none of the patients in the study were
smokers.
Platelet Rich Fibrin Membrane Preparation Protocol:
Based on the number of the teeth with gingival recession defects, ten to twenty 10ml
blood tubes were drawn for the patient before anesthesia was administered. Three to four A-PRF
membranes are recommended for each pair of treated teeth. The A-PRF tubes were immediately
spun in a centrifuge (Process Ltd.; Nice, France) at 1300 rpm (200 G) for eight minutes at room
temperature based on the A-PRF protocol (66). The A-PRF clots were removed from the tubes
and compressed in a special container and formed into membranes to be used for the clinical
application (Figure 2).
Surgical Protocol:
All patients were treated by FASTP protocol by an experienced periodontist in a private
practice setting. Surgery was done under moderate sedation and local anesthesia was
administered through block and/or infiltration. A flowable composite was placed and cured
between the teeth without any preparation (no etching or primer) to provide support for
interproximal sutures. This step is done at the beginning of the surgery to avoid any fluid
contamination for optimal bonding. Vertical vestibular incisions were done in appropriate
locations to allow access for instrumentation in order to advance a full thickness tunnel from the
vestibular mucosa to the marginal gingiva. Scaling, root planing, and root preparations were
12
done with hand instruments and a motor hand piece to create a flat or negative root surface. This
would allow more PRF membranes to be placed in the tunnel and yield in less flap tension.
Ethylene diamine tetraacetic acid (EDTA) 17% was applied on the root surfaces to remove the
smear layer created by the root preparation which would enable the collagen fibers of the tubule
to be exposed and thus improve the quality of the type of attachment expected. The full-thickness
tunnel was released sufficiently to allow for tension free advancement of the soft tissue 1-2mm
coronal to the CEJ of the teeth. PRF membranes were placed in the tunnel through the vestibular
incisions. Three to four membranes are recommended for each pair of treated teeth. If a
minimum of 2-3 mm keratinized attached gingiva was not present at the recession site, a sub-
epithelial palatal/tuberosity connective tissue graft was sutured at the site in the tunnel to
optimize the clinical outcome. These sites were excluded from the analysis. Apical periosteal
tacking mattress sutures (5.0 Polypropylene, Prolene, Henry Schein; Chatsworth, CA) were
placed to decrease tension from the marginal suture, and to stabilize and maintain the membranes
on the root surfaces and avoid any displacement of the membranes into the mucosal area.
Interproximal composite assisted sling sutures (6.0 Polypropylene, Prolene, Henry Schein;
Chatsworth, CA) were used to position the flap coronally. Multiple interrupted sutures (6.0
Polypropylene) were used to approximate the initial vestibular incisions (Figure 3). Patients were
prescribed antibiotics (Amoxicillin or Clindamycin), ibuprofen, and 0.12% chlorhexidine. Suture
were removed about 2.5 weeks after the surgery.
Intraoral Scan Evaluation:
Baseline and follow-up intraoral scans were taken using an optical scanner (3Shape
Trios) and saved in Standard Tessellation Language (STL) format. A reverse engineering
software (Geomagic Control X) was used by a single examiner (N.N.) to process the STL files
13
and perform the 3-D measurements. The first three cases were measured three times at different
timepoints for calibration and intra-examiner analysis. The preoperative and postoperative
digitalized images were cropped and superimposed. The “Global Registration” tool was used to
optimize the superimposition (Figure 4.A-C). A cross section in the middle of each tooth was
taken to confirm the complete superimposition of the buccal surface of each tooth (Figure 4.D).
The vertical dimension of the defects was measured from the gingival zenith to the
cementoenamel junction (CEJ) in millimeters (Figure 4. F). The horizontal measurement of the
defect was measured from the most mesial to most distal point on the defect of the marginal
gingiva in millimeters (Figure 4. F). Recession surface area was measured as the surface area of
the denuded anatomical root in squared millimeters (Figure 4.F). These two-dimensional
measurements were done separately on the preoperative and postoperative images before
superimposition.
The volumetric changes were quantified after the superimposition of preoperative and
postoperative images. After superimposition, each tooth was cropped from the midpoint of the
mesial and distal papilla (sagittal plane), 5 mm apical to the CEJ (transverse plane), and the
central groove or incisal edge of the teeth (coronal plane). The volumes of preoperative and
postoperative cropped images were subtracted from each other to calculate the volumetric
changes in cubic millimeters (Figure 4.H-I).
Statistical analysis:
Descriptive statistics and pre- and post-operative means and standard deviations were
calculated for all continuous descriptors. To address the primary aim, we reported the mean +
standard deviation of volumetric changes for the entire study population.
14
To address the secondary aim, we used a linear mixed model with a random intercept for
patients. We evaluated the following three-dimensional research questions: (1) does tooth
position predict volume gained? and (2) are there correlations between volume gained and
baseline measurements (defect’s depth, width, and surface area)? To address (1), we reported
marginal mean differences, 95% confidence intervals, and p-values. To address (2), we
calculated correlation coefficients, adjusted for repeated measures, and evaluated the linear
relationships between volume change and each of the baseline measurements. Model fit was
evaluated via inspection of residuals, outliers, and influence. We used Stata 15.0 (Statacorp,
College Station, TX) for all data management and to calculate and test predicted marginal mean
differences. To assess correlations between baseline measurements and the primary outcome, we
used the R package rmcorr (3.6.3 GUI 1.70 El Capitan build (7735), The R Foundation for
Statistical Computing) to calculate and test correlation coefficients, adjusted for repeated
measures.
A post-hoc power analysis was conducted, based on a linear model with a random
intercept and one predictor. We assumed a two-sided type I error rate of 5% and calculated
power for a range of possible effect sizes. Assuming a sample size of 150, we would have 80%
power to detect and effect size of r
2
=0.06, assuming the null hypothesis is r
2
=0. Larger effect
sizes will increase power whereas missing data will reduce power. Power was calculated using
G*Power Version 3.1.9.3.

15
RESULTS
The study sample consisted of 10 patients with a total of 144 (range 8-24 per patient)
gingival recession defects (RT1 = 21 defects, RT2 = 123 defects). All patients were non-smoker.
No complications were reported during the healing period. The mean recession depth, width, and
surface area at baseline was 1.7 ± 0.9 mm (range 0 - 5.2 mm), 4.2 ± 2.6 mm (range 0 – 9.7 mm),
10.4 ± 7.3 mm
2
(range 0 – 49.1 mm
2
), respectively (Table 2). The mean volume gain per tooth
was 7.9 ± 18.9 mm
3
(range -35.9 – 133.66 mm
3
). The mean volume gain for RT1 defects was
10.5 ± 30.0 mm
3
and for RT2 defects was 7.4 ± 16.5 mm
3
.
Table 3 exhibits the mean volume gain in different tooth positions. The mean volume
gain in a descending order was found to be 16.4 ± 32.6 mm
3
at maxillary canines, 14.8 ± 32.6
mm
3
at maxillary incisors, 7.8 ± 9.1 mm
3
at mandibular premolars/molars, 6.2 ± 16.4 mm
3
at
maxillary premolars/molars, 3.9 ± 11.0 mm
3
at mandibular canines, and 1.8 ± 7.7 mm
3
at
mandibular incisors. Based on these results, we rejected the first null hypothesis.
Table 4 presents the marginal mean differences in the volumetric changes when
comparing each tooth position to different groups. Maxillary canine had statically significant
more volume gain than mandibular teeth (p<0.05). In the maxilla, canines had statically
significant more gain than the posterior teeth (p<0.05). Maxillary incisors had statically
significant more gain than mandibular incisors (p = 0.01).
Table 5 presents the effect of baseline 2D measurements on the volumetric changes. Our
results revealed no statistically significant correlation between baseline recession depth, width,
surface area, and volume gain. Based on these results, we rejected our first null hypothesis but
could not reject our second null hypothesis.

16
DISCUSSION
Our study revealed that using FASTP protocol for root coverage therapy can increase the
soft tissue volume around treated teeth. Most root coverage studies report the changes in
recession depth and surface area. Different methods have been used in clinical studies to quantify
the 2-D and 3-D properties of gingiva and recession defects pre- and post-operatively, such as
periodontal probes, endodontic files, and optical scanning.
While the periodontal probe is the most common instrument used clinically to quantify
recession depth, width, and thickness of the gingiva, the accuracy of its measurement may be
limited. Limited access and visualization of the site, as well as the angulation of the tip of the
instrument can lead to errors in measurements. Moreover, most periodontal probes are marked at
1-3 mm intervals which decrease the accuracy of the readings (67). Our study utilized a novel
approach using digitalized images provided by an intraoral scanner which could overcome these
limitations. In addition, this would enable us to do the measurements multiple times without the
need of having the patient present.
While there is an abundance of clinical studies reporting the 2-dimensional changes after
root coverage procedures, data on quantifying the volumetric changes is scarce. We believe that
a 3-dimensional evaluation of soft tissue following root coverage procedure provides a more in
depth understanding of soft tissue changes after therapy. In a study by Lehmann et al., it was
demonstrated that the 3-dimensional optical method could give highly reproducible
measurements of volumetric changes in gingival recession (68).

17
The result of our study showed that there is an average of 7.9 mm
3
volume gain after a
mean of 12.2 months at sites treated with FASTP. Gil et al. reported the volumetric changes in
recession defects in humans treated with the VISTA technique with the addition of an
autogenous connective tissue graft, acellular dermal matrix, or xenogeneic collagen matrix (69).
In this study, an optical scanner was not used intraorally, however, digitalized pictures were
captured from the poured stone models of the patients. Their data showed a mean volume gain of
5.15 mm
3
and 6.05 mm
3
in RT I and RT II defects, respectively. Moreover, they reported no
intergroup statistically significant difference for different graft types and recession type (RT)
classes.
Schmitt et al. compared the volumetric changes around teeth in an animal study after soft
tissue augmentation was completed with either a subepithelial connective tissue graft or a
collagen matrix (70). Their 3-D tissue measurements immediately after surgery revealed a
significantly higher volume increase in the collagen matrix group (86.37 mm
3
) than in the SCTG
group (47.65 mm
3
). However, after 10 months, volume increase was not significant between
groups (SCTG:11.36 mm
3
; CM: 8.67

mm
3
), which showed a significant resorption or shrinkage
of the grafts.
Rebele et al. evaluated the three-dimensional changes in gingival recession defects
treated with the intrasulcular tunneling technique with an addition of subepithelial connective
tissue graft in humans (71). Their study did not quantify the volumetric changes; however, they
demonstrated 36% shrinkage in the augmented volume 12 months after therapy.
Our finding regarding the amount of volumetric changes is in line with the reported
volumes in Gil’s and Schmitt’s studies. This could propose that FASTP technique can be
18
considered a reasonable therapeutic modality for root coverage without a donor site morbidity.
Although our data presented a positive mean gain in the volume after therapy, our findings had
relatively high standard deviations. This may be due to patient-specific and site-specific
confounding factors and the limited number of patients.
Moraschini et al. published a systematic review on the use of PRF for treatment of
gingival recession (72). Their systematic review was done on 7 randomized controlled trials on
Miller class I and II defects comparing CAF, CAF+CTG, CAF+EMD, CAF+PRF. They
demonstrated that the use of PRF had several advantages: low cost, relatively simple acquisition,
no donor site morbidity, provide concentration of cytokines, immune cells, and growth factors,
suture suitability, potential to reduce postoperative symptoms, and accelerate tissue healing

through the stimulation of angiogenesis. However, the meta-analysis showed that the use of PRF
did not improve root coverage, clinical attachment level, or width of keratinized gingiva when
compared with the other therapeutic modalities. They attributed this to the relatively early
resorption of PRF.
On the other hand, Rodas et al. conducted a systematic review on PRF and gingival
recession in 2020 (73). This study compared data of 7 randomized controlled trials on Miller
class I and II for CAF+CTG and CAF+PRF. Interestingly, they showed no statistically
significant difference between the groups in terms of probing pocket depth, clinical attachment
level, and recession depth at 6-month follow-up. However, the CTG group showed statistically
significantly higher keratinized tissue width.
This discrepancy in the data could indicate that the use of PRF as a substitute to other
grafting biomaterials would not yield predictable outcomes. A possible explanation may be that
19
gingival recessions benefit from improving the thickness of the marginal gingiva, and PRF
membranes do not act as a solid scaffold. On the other hand, this discrepancy could be due to
confounding factors such as morphology of the defects, initial gingival thickness, number of
treated defects (single vs. multiple), tooth location, medical/smoking status of the treated
patients, different measurement protocols, different PRF preparation protocols, or the provided
surgical techniques.
Kobayashi et al. showed that A-PRF may result in superior clinical outcome due their
higher potential of growth factors released over 10 days after preparation when compared to PRP
and L-PRF (63).
Coronally advanced flap (CAF), intrasulcular tunneling (IST), and vestibular tunneling
(VISTA) are the most common techniques used in root coverage therapy. Chambrone et al.
reported that all these procedures can provide significant clinical improvements; however, each
technique may have some limitations (41).
Tavelli et al. compared the efficacy of the intrasulcular tunneling and coronally advanced
flap techniques (74). In this systematic review, it was shown that CAF demonstrated a superior
outcome in terms of root coverage. Despite its successful root coverage results, CAF might not
be the treatment modality of choice in the esthetic area since it can cause gingival scarring where
the incisions are placed.
Both intrasulcular and vestibular tunneling techniques were designed to overcome the
issue of scarring. The other advantages of tunneling techniques include undisrupted blood supply
to papillae and the underlying graft, faster healing, and reduced post-operative discomfort due to
the elimination of the separation between the buccal and palatal/lingual gingiva (75, 76).
20
On the other hand, tunneling techniques have some disadvantages, including limited access and
visibility for instrumentation and graft adaptation. Moreover, the bonded sutures on the facial
surface of the treated teeth in the VISTA technique could compromise the esthetics of these teeth
by the etching protocol, leaving residual resin after suture removal, and iatrogenic trauma to the
tooth surface when removing the excess resin. Additionally, presence of restorations may limit
the ability to bond sutures to labial teeth surfaces.
In FASTP surgical protocol, few modifications have been incorporated in the VISTA
technique to overcome these limitations, including: addition of multiple vestibular incisions as
needed to improve access, addition of apical mattress sutures to decrease the flap tension on A-
PRF clots and papillae, and the use of interproximal sling suturing to facilitate suture placement
and removal.
The secondary aim of our study was to investigate the relationship between tooth
position, defect’s depth, width, surface area and the volumetric changes. Our data showed that
tooth type/location plays a key role in determining the three-dimensional volume gain at the
recession sites. It was shown that maxillary canines and incisors have the best potential of
volume gain while mandibular incisors have the lowest potential for volume gain.
The significance of tooth location on root coverage has been studied in several clinical
trials. Aroca et al. studied the prognostic factors for root coverage in Miller III adjacent recession
defects treated with tunneling and CTG +/- EMD (77). This study showed that the distance from
the tip of the papilla to the contact point and tooth location are the key root coverage determining
factors. They reported that in general, maxillary teeth are more likely to have better root
coverage than mandibular teeth. Zucchelli et al. also evaluated the influence of tooth location on
21
determining the amount of root coverage with CAF (78). They reported that the second sextant is
associated with the highest root coverage outcomes (97%) compared with other sextants.
Moreover, mandibular anterior teeth showed the lowest root coverage (95% with CTG, 58%
without CTG). A practical explanation may be the unfavorable anatomic conditions in the
mandibular anterior area. High frenulum attachment, strong mentalis muscle pull, and shallow
vestibules are often present in this sextant, which can increase the flap tension and compromise
the clinical outcome.
The 2015 consensus report from the AAP regeneration workshop reviewed the patient-
related, site-related, and technique-related factors that may influence the final clinical outcome
after root coverage procedures (79). Regarding the site-related factors, presence of NCCLs and
recession defect depth were demonstrated to negatively affect the degree of root coverage. Gil et
al. also showed a statistically significant positive correlation between defect depth and volume
gain (69). However, our result showed that the defect’s depth, width, and surface area at baseline
did not have any statistically significant impact on the volumetric changes in the gingiva.
This discrepancy could be due to the differences in measurements techniques. We
measured the dimensions of the defect directly on the digitalized images captured with an
intraoral scanner. Most studies use a periodontal probe clinically to measure the depth of the
defects which might be less accurate than digitalized measurements. In Gil’s study, the
digitalized measurements were done on images captured from stone models which undergo some
degree of shrinkage. Moreover, it has been shown in literature that initial gingival thickness
plays a significant role in the final outcome of root coverage therapies. We believe that the
22
baseline gingival thickness and the surgical techniques could also contribute to these
discrepancies in data.
The use of biomaterials such as autogenous connective tissue grafts and allogenic
acellular dermal matrices in root coverage procedures have been vastly studied (21). These grafts
have shown promising results as a means to increase the thickness of the gingiva. Moreover, in
classic literature, the significance of underlying connective tissue on surface epithelium
differentiation has been reported by Karring (80).
The basis of the Fibrin Assisted Soft Tissue Promotion technique is not adding a graft (ie.
CTG, ADM…) to alter the biology of the recipient site. Instead, PRF concentrates are used as a
scaffold of growth factors to promote angiogenesis and tissue regeneration at the defective
recipient site. It has been shown that PRF membranes resorb in 10-14 days; therefore, the
increased volume shown in our study may be a regenerated tissue. For this reason, we believe the
quality of the recipient site plays a major role in the final outcome after therapy. If the defective
recipient site has a band of keratinization, then the growth factors would promote new tissue
regeneration with the same characteristics. However, if the recipient site presents with a thin
mucosal tissue, the final regenerated tissue will be non-keratinized as well. Our result showed
that maxillary anterior teeth had significantly more volume gain after therapy. We strongly
believe that this is also attributed to the quality of the tissue at baseline since maxillary anterior
teeth usually have a wider band of keratinized tissue.
Our study presents some limitations that should be addressed in future studies, including:
a) the retrospective nature of the study, b) lack of a negative control group to evaluate the
efficacy of FASTP alone, c) lack of a positive control group with the use of CTG, d) short-term
23
study follow up, and e) small sample size. In addition, in some of our cases connective tissue
graft was utilized in localized areas that presented with <3mm of band of keratinization. While
these teeth were excluded from our analysis, they may have an impact on the final outcome of
the adjacent teeth.
Our study provides a proof of principle which states that FASTP technique may be used
as a technique for root coverage therapy at sites that present with keratinized gingiva. Additional
long-term randomized clinical trials with a negative control and larger patient pool are needed to
investigate the efficacy of this novel technique. Moreover, histologic analyses are critical to
evaluate the nature of the attachment of the tissue to the root surface after healing.

24
CONCLUSION
1- Use of the “fibrin-assisted soft tissue promotion” protocol for treatment of multiple adjacent
gingival recession defects (RT1 & RT2) yielded in an increase in gingival volume around the
treated teeth.
2- The treated maxillary canines and incisors had the highest amount of volume gain, while
mandibular incisors had the lowest amount of volume gain.
3- There was no correlation found between the defect’s depth, width, surface area and the
volume change.
4- Computerized intra-oral scan analyses is a practical technique to examine 2-D and 3-D
changes in periodontal plastic surgeries.

25
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32
TABLES
Table 1: Demographic of the sample population (N = 10)

Variables

Age (year)
Mean ± SD
Range

49.6 ± 12.6
25 - 65
Sex
Female
Male

n = 6
n = 4
Race
Caucasian
Asian

n = 8
n = 2
Medical Status
ASA I
ASA II
n = 8
n = 2

33
Table 2: Descriptive statistics of defect characteristics

Mean ± SD Range
Follow-up Period (months) 12.2 ± 4.6 6 – 18
Defect Depth (mm) 1.7 ± 0.9 0 – 5.2
Defect Width (mm) 4.2 ± 2.6 0 – 9.7
Defect Surface Area (mm
2
) 10.4 ± 7.3 0 – 49.1
Volume Change (mm
3
) 7.9 ± 18.9 -35.9–133.7

34
Table 3: Mean volumetric changes for each tooth position group
Tooth Position Volume Change mm
3

N Mean ± SD
Maxillary Premolars + First Molar 42 6.2 ± 16.4
Maxillary Canines 15 16.4 ± 32.6
Maxillary Incisors 17 14.8 ± 32.6
Mandibular Premolars + First Molar 38 7.8 ± 9.1
Mandibular Canines 9 3.9 ± 11.0
Mandibular Incisors 23 1.8 ± 7.7

35
Table 4: Predicted marginal mean differences in volume change (mm
3
)
Tooth
Position
Maxillary
Premolars
+ First
Molar
Maxillary
Canines
Maxillary
Incisors
Mandibular
Premolars
+ First
Molar
Mandibular
Canines
Mandibular
Incisors
Maxillary
Premolars +
First Molar
-- 10.8 (0.5,
21.1)
p =0.039*
7.3 (-2.7,
17.3)
p=0.151
-0.4 (-8.4,
7.6)
p=0.922
-4.8 (-17.6,
8.0)
p=0.465
-6.7 (-15.8,
2.5)
p=0.154
Maxillary
Canines
-- -- -3.5 (-15.7,
8.7)
p=0.577
-11.2 (-21.9,
-0.5)
p=0.040*
-15.6 (-30.2,
-0.9)
p=0.037*
-17.5 (-29.1,
-5.8)
p=0.003*
Maxillary
Incisors
-- -- -- -7.7 (-18.1,
2.6)
p=0.144
-12.1 (-26.5,
2.3)
p=0.100
-14.0 (-25.2,
-2.7)
p=0.015*
Mandibular
Premolars +
First Molar
-- -- -- -- -4.4 (-17.1,
8.4)
p=0.500
-6.3 (-15.3,
2.8)
p=0.178
Mandibular
Canines
-- -- -- -- -- -1.9 (-15.5,
11.7)
p=0.787
P-values were obtained using multilevel mixed-effects linear regression. Each cell presents
marginal mean differences between groups, 95% confidence intervals, and p-values. Dashes
indicate comparisons that were already presented in the table. Positive numbers indicate an
increase for teeth in the columns vs. teeth displayed in the rows.

36
Table 5: Correlations between baseline measurements and volume change (adjusted for repeated
measures)

Volume Change
(r and 95% CI)
p-value
Recession Depth 0.02*
(-0.16, 0.21)
0.803
Recession Width 0.08
(-0.09, 0.25)
0.354
Recession Surface Area 0.01
(-0.18, 0.20)
0.923

* = mm
3
volume change per unit of the corresponding variable. Positive correlation coefficients
indicate an increasing linear trend, while negative correlation coefficients indicate a decreasing
linear trend.

37
FIGURES
Figure 1.1. Comparative release of PDGF from PRP, L-PRF, and A-PRF over 10 days after
preparation (Kobayashi et al. 2016).

38
Figure 1.2. Comparative release of TGFβ1 and VEGF from PRP, L-PRF, and A-PRF over 10
days after preparation (Kobayashi et al. 2016).

39
Figure 1.3. Comparative release of EGF and IGF from PRP, L-PRF, and A-PRF over 10 days
after preparation (Kobayashi et al. 2016).

40
Figure 2: Advanced Platelet Rich Fibrin (A-PRF) membrane preparation. A: fibrin clot
dissociation from red blood cells after centrifugation, B: fibrin clots, C: fibrin membranes after
compression

41
Figure 3: Treatment of multiple adjacent gingival recession defects (RT1 & RT2) with FASTP
protocol. A: Baseline, B: vestibular incision, C: Tension-free coronal advancement through
vestibular incision, D: root surface preparation with 17% EDTA, E: introduction of A-PRF
membranes through the vestibular incision, F: clinical presentation after placing 3-4 A-PRF
membranes per pair of treated teeth, G: Apical periosteal mattress sutures, H: interproximal
resin assisted sutures, I: 24-month postoperative presentation

42
Figure 4: 3-Dimentional Image Translated from Intraoral Scan. A: Cropped image of the pre-
operative condition B: Cropped image of the post-operative condition C: Image A and B
superimposed D: Cross-section (sagittal plane) mid facial tooth #8 to confirm superimposition E:
Cropped facial view of pre-operative tooth #8 F: Red = recession surface area, Arrows = defect
depth and width G: Cropped facial view of post-operative tooth #8 H: 3-D view of cropped pre-
operative tooth #8 I: 3-D view of cropped post-operative tooth #8 Volume Change = volume of
H – volume of I

43
Figure 5: Volumetric changes (mm
3
) distribution for each tooth position group

44
Figure 6: Mean volumetric changes (mm
3
) for each tooth position group

* = statistically significant (P < 0.05)

Abstract (if available)

Abstract A variety of surgical techniques and biomaterials have been introduced to treat multiple adjacent gingival recession defects. While there is an abundance of clinical studies reporting 2-dimensional changes after root coverage procedures, data on evaluating 3-dimensional changes is scarce. The primary aim of this retrospective study is to assess the volumetric changes around teeth with gingival recession defects with Fibrin-Assisted Soft Tissue Promotion (FASTP) technique using Advanced Platelet Rich Fibrin (A-PRF) membranes. The secondary aim was to analyze the correlation between baseline defect depth, width, surface area, tooth position and the volumetric changes after healing. ❧ Methods: This study is designed as a retrospective analysis. Pre- and post-operative intraoral scans of 10 patients (144 teeth: 23 RT1 + 121 RT2) treated with FASTP were digitally superimposed to quantify volumetric changes around each treated tooth. ❧ Results: The mean volume gain per tooth in a descending order was 16.4 ± 32.6 mm³ at maxillary canines, 14.8 ± 32.6 mm³ at maxillary incisors, 7.8 ± 9.1 mm³ at mandibular premolars/molars, 6.2 ± 16.4 mm³ at maxillary premolars/molars, 3.9 ± 11.0 mm³ at mandibular canines, and 1.8 ± 7.7 mm³ at mandibular incisors. Maxillary canine had significantly more volume gain than mandibular teeth (p<0.05). In the maxilla, canines had significantly more gain than the posterior teeth (p<0.05). Maxillary incisors had significantly more gain than mandibular incisors (p = 0.01). No statistically significant correlation was found between baseline recession depth, width, surface area, and volume gain. ❧ Conclusion: The present findings suggest that FASTP technique may be used for root coverage therapy at sites that present with keratinized gingiva.

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Asset Metadata

Creator Nobaharestan, Navid (author)

Core Title Efficacy of fibrin-assisted soft-tissue promotion (FASTP) in treatment of multiple gingival recession defects: a retrospective 3-D volumetric analysis

School School of Dentistry

Degree Master of Science

Degree Program Craniofacial Biology

Publication Date 07/23/2020

Defense Date 05/20/2020

Publisher University of Southern California (original), University of Southern California. Libraries (digital)

Tag gingival augmentation,gingival recession,OAI-PMH Harvest,platelet rich fibrin,PRF,root coverage

Language English

Contributor Electronically uploaded by the author (provenance)

Advisor Bakhshalian, Neema (committee chair), Kar, Kian (committee member), Navazesh, Mahvash (committee member)

Creator Email navid.stan@gmail.com,nnobahar@usc.edu

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c89-343090

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Source University of Southern California (contributing entity), University of Southern California Dissertations and Theses (collection)

Access Conditions The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the a...

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